A trend is something that somehow becomes popular
within mainstream society over a long period of time. It is the
direction of a sequence of events that has some momentum and
durability.

A fad is something that is very popular with a
small group of people for a short period of time.

A craze is often interchanged with a fad by which
it describes a product, idea, cultural movement or model that gains
popularity among a small section of the populace then quickly
migrates to the mainstream. Crazes are
characterized by their lightning fast adoption and just as swift
departure from public awareness. Crazes and fads are also
characterized by their unusually high interest/sales figures
relative to the time they are active in the marketplace as compared
with other similar products, ideas, cultural movements or
models.

It is interesting to note that, despite the
negative or counterproductive results of crazes and fads, some
respectable companies still around today got their start by
purposely or accidentally creating a fad or craze. Examples
include:

Starbucks
Coffee: Howard
Schultz returned to the U.S. after spending time in Italy. He
noticed how coffee bars were very popular there and introduced the
concept to Americans. Due to the novelty of buying an expensive,
robust coffee product in a comfortable cafe, Americans quickly
spread positive word-of-mouth
creating a craze.